Laser three-dimensional printing forming and photosensitive liquid solidify, stereo lithography, three-dimensional modeling, rapid prototyping method is a kind of the earliest, is currently the world's most in-depth study, the most mature technology, the most widely used a kind of rapid prototyping method. The photosensitive resin (such as propylene based resin) as raw material, point by point scanning trajectory profile information using ultraviolet5000mw laser pointerunder computer control in a predetermined section of the prototype of each layer, the scanning is generated after the polymerization reaction of light cured resin layer region, thereby forming a thin section. When a layer is solidified, the working table is moved downward (or upward), and a new liquid resin is arranged on the surface of the newly cured resin, and then a new layer of scanning and curing is carried out. The new curing a layer of adhesive in the first layer, to repeat the entire prototype manufacturing. The fabrication process is dependent on the laser beam selectively curing a thin layer of photosensitive polymer, which is finally solidified to form a three-dimensional object.

The forming device is also called "stereo lithography equipment", is a product of rapid prototyping machine first appeared in the tank, it consists of lifting worktable, high power laser pointer scanning system and computer control system etc.. The tank filled with liquid photosensitive polymer (usually 20~200L). The lifting table with a plurality of small holes can be driven by the stepper motor to move along the direction of height Z. The laser is ultraviolet (UV) laser, such as helium cadmium (He-Cd) laser, argon ion (Ar) laser and solid state laser, its power is generally 10 to 200mW, the wavelength is from 320 to 370um (in the ultraviolet to near ultraviolet band). Scanning system for a group of positioning mirror, it can according to the command of a control system for high speed reciprocating swing according to each section outline requirements, so that the laser beam is focused on the surface of the reflection emit in a liquid photosensitive polymer bath, scanning motion and direction along the surface of the X-Y. In this layer by UV laser irradiation of the site, liquid photosensitive polymer fast curing, the formation of a corresponding solid section profile. SLA forming, laser beam scanning according to the NC instruction, lifting the upper surface of the table in the next section the liquid layer height (usually 0.125 to 0.75mm), the layer of liquid photosensitive polymer by 500mw laser pointer scanning polymerization and curing, and form the desired first layer of solid state profile after work Taiwan down a layer of high profile, a photosensitive polymer layer of liquid flowing through the flume has solidified, scraper according to the set height for reciprocating motion, scrape excess polymer, then scan curing on this layer with new liquid polymer, formed second layers required solid section profile, a new curing layer can a firm bond in the previous layer, so repeated until the entire processing is completed, a 3D prototype.

In 1988, the United States 3DSystem company first produced the world's first SLA250 type liquid photosensitive resin for selective brightest laser pointer curing rapid molding machine, its recently launched office desktop 3D printer CubePro and Cube Pro, is the 3D printing technology to civilian. In addition, the world is engaged in the research of the technology, as well as EOS, MEC and CMET, a subsidiary of Mitsubishi Co, etc.. In recent years, 3D System has adopted a new technology called Zephyer Recoating System, the technology is forming in each layer, the layer is coated with a layer of 0.05~0.1mm for curing resin using a vacuum adsorption type scraper, to shorten the average time of forming 20%.

The research of SLA forming technology in China has Xi'an Jiao Tong University, from 1993, the key technology and material of the light cured resin forming machine with good forming quality and high speed are selected as the breakthrough point. Strong support in the country, in cooperation with Shaanxi Hengtong only machine equipment Co. Ltd, has developed to the market out of the first domestic LPS, SPS and CPS light cured resin material forming machine and supporting.

Shaanxi Hengtong in hardware and software technology advantages mainly as follows: the resin material for foreign half; self-developed software more powerful; vacuum adsorption resin coating system, which improves the speed and quality of the shell parts. At present, three-dimensional printing forming technology mainly has following several aspects: the forming mechanism is not clear, need to solve these problems from the experimental research and theoretical analysis on SLA; the product cost is higher; forming material is single, still need to be diversified; the forming precision is low 2000mw laser pointer; forming parts with low strength.